1. Field of the Invention
The present invention relates to a display system for vehicles, in particular commercial vehicles, as well as to a method for displaying a display image to the driver of a vehicle, in particular a commercial vehicle.
2. Description of the Related Art
Usually, vehicles are equipped with systems for indirect vision to the immediate environment of the vehicle, as, for example, side mirrors. In commercial vehicles, for example, a main mirror is provided on both the driver's side and the passenger's side as a device for indirect vision, by means of which the driver may view a plane and horizontal part of the lane having a specified width, which extends from a predetermined distance behind the driver's eye point up to the horizon. A strip of smaller width is also visible for the driver by means of these mirrors; this strip, however, already begins at a shorter distance behind the driver's eye point.
Additionally to these main mirrors, wide-angle mirrors are provided on both sides of the vehicle, by means of which a respective portion behind the driver's eye point is visible up to a predetermined distance in the longitudinal direction of the vehicle, said portion being broader than the portion being visible by means of the main mirror, but only extending to a predetermined length along the vehicle.
Further, parking assistance systems for passenger vehicles are known, where a display inside the vehicle may display at least a stylized representation of the passenger vehicle from a bird's eye view. Sensors may capture an immediate vehicle environment. If an obstacle is determined, corresponding signals on the display start blinking.
In recent times, it has been increasingly considered to use, additionally to conventional mirrors as systems for indirect vision, camera systems or image capturing systems as systems for indirect vision, either in addition to or as replacement for said mirrors. In these image capturing systems, an image capturing unit continuously captures an image, and the (video) data captured by the image capturing unit are, for example by means of a calculation unit and, if necessary, after further processing, supplied to a rendering unit within the driver's cabin where the vehicle environment and possibly additional information as, for example, watch notices, distances and the like for the area around the vehicle are continuously and visibly displayed to the driver.
Despite these prescribed mirrors or systems for indirect vision, however, it is hardly possible or at least very difficult for a driver to always completely and adequately keep in view the critical areas around a commercial vehicle. Moreover, due to the number of mirrors, it is hard for the driver to simultaneously view these mirrors.
Especially in commercial vehicles like trucks, busses, etc. visibility is critical on the driver's sides. Obstacles or other road users are poorly recognized, as the blind angle ranges are relatively large and, thus, obstacles as, for example, other road users are not visible in the system for indirect vision. Moreover, orientation is difficult for the driver due to the comparatively large number of devices for indirect vision, so that there is the danger of overlooking obstacles, in particular when turning or shunting, although these obstacles are depicted in the system for indirect vision. Consequently, accidents are often caused due to the fact that the driver of the commercial vehicle does not adequately view areas on the side of the vehicle, in particular in the dead angle ranges, which are an area at the side of the vehicle, which is non-visible or only poorly visible for the driver despite the above described exterior mirrors.
It is therefore known to mark obstacles on a rendered image by graphical display as, for example colored frames or the like. Acoustic or visual warning signals by means of loudspeakers or light effects are also known as a means for indicating obstacles in the vehicle's immediate environment. Here, it is disadvantageous that the graphical displays conceal parts of the rendered image and, thus, the exact location of the obstacle on the rendered image may often be unclear or orientation for the driver may be more difficult.
DE 10 2011 010 624 further discloses a display system for legally prescribed fields of vision of a commercial vehicle within a driver's cabin of the commercial vehicle, the display system comprising at least a display unit adapted to display at least two of the legally prescribed fields of vision permanently and in in real time on the display unit in the driver's cabin.
U.S. Pat. No. 8,810,381 B2 discloses a head-up display for a vehicle having a collision warning system. Here, various points of information are projected in series on the windshield, which is superimposed by the real image that is directly perceived by the driver.
U.S. Pat. No. 7,592,928 B2 discloses a system and method for image representation, which enables monitoring any differences between the relative position of an obstacle as it appears in an image representation in the bird's eye view, and its current relative position, on the same display. For this purpose, an image in the bird's eye view is generated from a number of captured images, which image shows the vehicle environment. Then, the image in the bird's eye view and an individual image captured by the camera are simultaneously displayed, in case an obstacle has been determined in the vehicle environment.
Further drive assistance systems are known from U.S. Pat. No. 8,305,204 B2, US 2014/0118551 A1, US 2008/0205706 A1, and U.S. Pat. No. 8,305,444 B2.
In the known systems and methods at least one real image, which is usually captured by a camera, is displayed by a rendering unit in real time and visible for the driver in order to provide the driver with insights of poorly visible areas. The real images captured by the camera are a detailed representation of the scenery in the vehicle's environment at the time of recording. Thus, the real images captured by the camera comprise an abundance of information, and not all of this information may be of interest for the driver of the vehicle.